#include <stdio.h>

int main()
{
	float C1 = 0, C2 = 0;
	int hour = 0, min = 0, sec = 0, time = 0;

	scanf("%f %f", &C1, &C2);

	if((float)(C2 - C1) / 100 - (int)(C2 - C1)/100){
		time = (int)(C2- C1) / 100 + 1;
	}
	else{
		time = (int)(C2 - C1) / 100;
	}

	while(1){
		time = time - 60;
		if(time > 0){
			sec = time;
			min++;
			if(min == 60){
				hour++;
				min = 0;
			}
		}
		else{
			break;
		}
	}
	printf("%02d:%02d:%02d\n", hour, min, sec);
	return 0;
}
